﻿// SAX locator interface for document events.
// http://www.saxproject.org
// No warranty; no copyright -- use this as you will.
// $Id$
using System;

namespace org.xml.sax
{

    /**
     * Interface for associating a SAX event with a document location.
     *
     * <blockquote>
     * <em>This module, both source code and documentation, is in the
     * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
     * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
     * for further information.
     * </blockquote>
     *
     * <p>If a SAX parser provides location information to the SAX
     * application, it does so by implementing this interface and then
     * passing an instance to the application using the content
     * handler's {@link org.xml.sax.ContentHandler#setDocumentLocator
     * setDocumentLocator} method.  The application can use the
     * object to obtain the location of any other SAX event
     * in the XML source document.</p>
     *
     * <p>Note that the results returned by the object will be valid only
     * during the scope of each callback method: the application
     * will receive unpredictable results if it attempts to use the
     * locator at any other time, or after parsing completes.</p>
     *
     * <p>SAX parsers are not required to supply a locator, but they are
     * very strongly encouraged to do so.  If the parser supplies a
     * locator, it must do so before reporting any other document events.
     * If no locator has been set by the time the application receives
     * the {@link org.xml.sax.ContentHandler#startDocument startDocument}
     * event, the application should assume that a locator is not 
     * available.</p>
     *
     * @since SAX 1.0
     * @author David Megginson
     * @version 2.0.1 (sax2r2)
     * @see org.xml.sax.ContentHandler#setDocumentLocator 
     */
    public interface Locator
    {


        /**
         * Return the public identifier for the current document event.
         *
         * <p>The return value is the public identifier of the document
         * entity or of the external parsed entity in which the markup
         * triggering the event appears.</p>
         *
         * @return A string containing the public identifier, or
         *         null if none is available.
         * @see #getSystemId
         */
        String getPublicId();


        /**
         * Return the system identifier for the current document event.
         *
         * <p>The return value is the system identifier of the document
         * entity or of the external parsed entity in which the markup
         * triggering the event appears.</p>
         *
         * <p>If the system identifier is a URL, the parser must resolve it
         * fully before passing it to the application.  For example, a file
         * name must always be provided as a <em>file:...</em> URL, and other
         * kinds of relative URI are also resolved against their bases.</p>
         *
         * @return A string containing the system identifier, or null
         *         if none is available.
         * @see #getPublicId
         */
        String getSystemId();


        /**
         * Return the line number where the current document event ends.
         * Lines are delimited by line ends, which are defined in
         * the XML specification.
         *
         * <p><strong>Warning:</strong> The return value from the method
         * is intended only as an approximation for the sake of diagnostics;
         * it is not intended to provide sufficient information
         * to edit the character content of the original XML document.
         * In some cases, these "line" numbers match what would be displayed
         * as columns, and in others they may not match the source text
         * due to internal entity expansion.  </p>
         *
         * <p>The return value is an approximation of the line number
         * in the document entity or external parsed entity where the
         * markup triggering the event appears.</p>
         *
         * <p>If possible, the SAX driver should provide the line position 
         * of the first character after the text associated with the document 
         * event.  The first line is line 1.</p>
         *
         * @return The line number, or -1 if none is available.
         * @see #getColumnNumber
         */
        int getLineNumber();


        /**
         * Return the column number where the current document event ends.
         * This is one-based number of Java <code>char</code> values since
         * the last line end.
         *
         * <p><strong>Warning:</strong> The return value from the method
         * is intended only as an approximation for the sake of diagnostics;
         * it is not intended to provide sufficient information
         * to edit the character content of the original XML document.
         * For example, when lines contain combining character sequences, wide
         * characters, surrogate pairs, or bi-directional text, the value may
         * not correspond to the column in a text editor's display. </p>
         *
         * <p>The return value is an approximation of the column number
         * in the document entity or external parsed entity where the
         * markup triggering the event appears.</p>
         *
         * <p>If possible, the SAX driver should provide the line position 
         * of the first character after the text associated with the document 
         * event.  The first column in each line is column 1.</p>
         *
         * @return The column number, or -1 if none is available.
         * @see #getLineNumber
         */
        int getColumnNumber();

    }

    // end of Locator.java
}